A flexible display device includes an array substrate, a display medium layer, a transparent substrate and a first sealant. The array substrate has a display region and a sealant spread region surrounding the display region. The display medium layer is disposed on the array substrate and located in the display region. The transparent substrate is disposed above the display medium layer. The first sealant is formed between the array substrate and the transparent substrate and located in the sealant spread region of the array substrate. The first sealant has a first sidewall and a second sidewall. One of the first sidewall and the second sidewall has a plurality of fillisters arranged at intervals. Since the first sealant of the flexible display device has the fillisters arranged at intervals, the stress imposed on the first sealant may be decreased. Therefore, the life of the first sealant may be prolonged and the sealing performance of the flexible display device can be improved.